In a known manner, a suspension system comprises a strut supporting an axle and a wheel of a vehicle. A suspension bearing device is placed in the top portion of the strut, opposite to the wheel and the ground, between a suspension spring and an upper member secured to the body of the vehicle. The spring is placed around a damper piston rod of which the end may be secured to the body of the vehicle.
WO-A-2011/012484 discloses an example of a suspension bearing device, comprising a rolling bearing, a lower cup and an upper cup. The suspension bearing device is configured for transmitting loads between a suspension spring and the body of the vehicle, while allowing a relative angular movement between the races of the rolling bearing. The lower cup includes a metal stiffening insert to have a high enough rigidity and to allow the transmission of high axial and radial loads. The lower cup also includes a flexible member, comprising an annular ring and two seals connected to the annular ring by axial studs.
The seals are designed to protect the bearing against infiltrations of water or pollutant particles, while the annular ring is designed to absorb in part the vibrations and shocks generated by the suspension spring. However, inconvenient noise can be generated in case of important vibrations. In that case, the axial damping effect of the annular ring is not fully satisfactory due to its small thickness. Besides, the suspension spring can radially collide with the rigid body of the lower cup. Consequently, the car manufacturer usually arranges an additional damping component, namely a rubber insulator, between the suspension bearing device and the suspension spring.